Shinya Matsuzaki Maskawa Institute for Science and Culture, Kyoto Sangyo Univ.

@KMI, Nagoya Univ. 03/18/2012

Techni-dilaton at LHC

Contents of this talk

Techni-dilaton couplings

Walking Technicolor and Techni-dilaton

Introduction & brief summary

Techni-dilaton signatures at LHC

Summary

Introduction & brief summary

ATLAS-CONF-2012-019 CMS-PAS-HIG-12-008

2011 LHC Higgs search

SM Higgs: excluded in the most of mass range up to 600 GeV

--- implies: the mass is unlikely to be as low as O(EW)?

ATLAS-CONF-2012-019CMS-PAS-HIG-12-008

Even in low-mass range: a hint from diphoton channel

The best fit-signal strength σ/σSM|γγ ～ 2 --- also implies a non-SM like Higgs object at ～ 125 GeV?

This talk will tell us two non-SM like Higgs scenarios:

light TD: can explain the presently observed diphoton excess at around 125 GeV

(somewhat) heavy TD : can be seen in diphoton channel as an excessive non-resonant signal above 600 GeV

based on S.M. and K. Yamawaki, arXiv: 1201.4722 [hep-ph]; arXiv: 1203.xxxx [hep-ph] (in preparation)

based on S.M. and K.Yamawaki, Prog.Theor.Phys. 127 (2012); arXiv: 1203.xxxx [hep-ph] (in preparation)

Techni-dilaton (TD): a composite scalar, characteritic in walking technicolor (WTC)Yamawaki et al (1986); Bando et al (1986)

Quick view of main result on TD at ～ 125 GeV

* The signal strengths (γγ, WW*,ZZ*) are in good agreement with the best-fit ones!!

S.M. and K. Yamawaki, arXiv:1201.4722; 1203.xxxx.

WW* ZZ* γγ

Quick view of main result on heavy TDS.M. and K. Yamawaki, PTP127 (2012). arXiv: 1203.xxxx.

WW ZZ

ATLAS03/07/12

CMS03/07/12

* 140 GeV < M < 600 GeV excluded

Above 600 GeV: * huge total width > O(TeV) non-resonant * highly enhanced diphoton signal w/ σ(pp->TD-> 2γ) ～ O(fb)

Walking Technicolor and Techni-dilaton

Technicolor (TC) Walking TC

TC: origin of mass dynamical explanation for EWSB techni-fermion condensation like quarks in QCD

TC dynamics should be non QCD-like: FCNC syndrome

Weinberg (‘76), Susskind (‘79)

Yamawaki et al (1986); Bando et al (1986)

Be “Walking” Holdom (1981); Yamawaki et al (1986); Bando et al (1986); Akiba et al (1986); Appelquist et al (1986); (1987)

The explicit proposal based on ladder SD eq analysis

To solve FCNC problem

QCD-like

QCD-like

QCD-like

“walking”

(ETC~10^3TeV)(~1TeV)

A schematic view of Walking TC

replaced by

*Dynamical TF mass generation by WTC @μcr

“Miransky scaling”Miransky (1985)

(solve FCNC problem)

A schematic view of Walking TC

QCD-like

QCD-like

QCD-like

“walking”replaced by

(~1TeV) (ETC~10^3TeV)

(naturalness)

(approx. scale invariance)

Large Nf QCD: a realistic dynamics for walking TC

Application to TC

“pseudo-FP”

*Conformal window (CW)

*criticality condition:Appelquist et al (1996)

based on ladder SDeq analysis

set α* at a little outside of CW

Yamawaki et al (1986); Bando et al (1986)

walking regime

(Approximate) scale-invariance in WTC presence of (p)NGB for scale symm = “dilaton”.

WTC and techni-dilaton

WTC and techni-dilatonYamawaki et al (1986); Bando et al (1986)

SSB by TF mass generation @ mu_cr

walking regime

(Approximate) scale-invariance in WTC

(p)NGB for scale symm “dilaton” emerges

nonperturbative scale anomaly

NP

makes dilaton massive: “techni-dilaton” (pNGB) potentially light!

TC

WTC and techni-dilatonYamawaki et al (1986); Bando et al (1986)

NP

α starts “running” (walking) up to mF

SSB by TF mass generation @ mu_cr

walking regime

(Approximate) scale-invariance in WTC

(p)NGB for scale symm “dilaton” emerges

Cf: naive scale-up version of TC

Light composite scalar Higgs in naive scale-up version of QCD?

scale symmetry is badly broken at perturbative level (cf. QCD)

typical TC hadron mass scale

No reason to be ligher than other TC hadrons

Techni-dilaton is chiral-singlet, FF bound state

TC sector dilataion current = chiral singlet

TD: pNGB associated with SSB of scale symm.

Chiral singlet partChiral field

w/ scale dim. of

NOT “ σ ” as a chiral partner of π (c.f. composite Higgs)

TC

TC TC

TC

PCDC (partially conserved dilatation current)

TC TC

* PCDC based on the Ward-Takahashi identity:

* TG condensation induced by TF condensation during walking

walking regime

PCDC (partially conserved dilatation current)

TC TC

* TG condensation induced by TF condensation during walking

walking regime

which has nothing to do w/ TG self-condensation outside walking region (pert. running region)

* PCDC based on the Ward-Takahashi identity:

so it is expected to generically scale like All the scale in the condensation should come from m_F

Miransky et al (1989): ladder approx. w/ constant couplingHashimoto et al (2011): improved ladder w/ two-loop beta func.

finite

Straightforward non-pert. cals:

even at criticality limit

No exactly massless NGB limit for TD

PCDC finite

implies:TD cannot be massless unless Fφ ∞: decoupled No exactly massless NGB limit!

reflecting non-pert. scale anomaly (explicit breaking) induced by mF generation itself

Straightforward calculation of TD mass?

* LSD + BS in large Nf QCD

* LSD via gauged NJL

Harada et al (1989); Kurachi et al (2006)

Shuto et al (1990); Bardeen et al (1992); Carena et al (1992) ; Hashimoto (1998)

chiral NON-singlet “σ” mass

Mσ ～ 500 – 600 GeV for one-family model

But, Mσ may not be Mφ .... ?

No conclusive answer yet.... (theoretically unknown : Mφ as free/input parameter)

Techni-dilaton couplings

S.M. and K. Yamawaki, PTP127 (2012). arXiv: 1203.xxxx.

TD coupling to techni-fermions

* Ward-Takahashi identity

TC

Full propagator^-1

mass func. in walking regime

w/

TD coupling to techni-fermions

* Ward-Takahashi identity

TC

TD pole Full propagator^-1

mass func. in walking regime

w/

Yukawa vertex func. c.f. GT relation for pion coupling to nucleons in QCD

TD couplings to SM particles

* SM particles do not directly couple to TD:

TC

transform

Couplings are generated only through TF - loops

ETC 4-fermi

* TD coupling to SM fermions

SM f-fermion mass

TF condensation w/

Yukawa coupling to SM-fermion

* TD couplings to SM gauge bosons

V-gauge boson self-energy func.

For weak bosons:

related to broken axialvector TF current

TD-WW coupling (mass coupling form): with

Note:

In addition, higher-order WW coupling arises:

transverse partone-loop approx.

SU(2) beta func. including only TF-loop contributions

In TF decoupling limit: p^2/mF^2 0

TD-WW coupling (field strength form):

For couplings to diphoton and gluons = similar field strength forms

with

Thus, TD couplings to SM particles are essentially the same as those for the SM Higgs!

Just a simple scaling from the SM Higgs:

TD LHC study is doable!

(note: φ-gg, φ-γγ depending highly on particle contents of WTC models )

with

Estimate of TD coupling

* PCDC

* Pagels-Stokar formula Appelequist et al (1996)

criticality condition

* Recent LSD analysis (large Nf QCD)Hashimoto et al (2011)

# of TFs

EW-doublets ``dummy”

one-doublet model (1DM)

one-family model (1FM)

TD coupling is suppressed almost all over the mass range 110 GeV < M < 600 GeV! (non-SM Higgs like)

• only two-body decays taken into account• SM –loop corrections incorporated

The total width (1FM) up to 600 GeV

SM Higgs

TD

Narrow resonant (gφ<ghiggs)

Broad non-resonant

• only two-body decays taken into account• SM –loop corrections incorporated

The total width (1FM) up to 600 GeV

SM Higgs

TD

Jia-Matsuzaki-Yamawaki, in preparation

Narrow reasonant (gφ<ghiggs)

Broad non-reasonant

* decays to color-triplet techni-pions P3^+-00’ open to be dominant

Techni-dilaton signatures at LHC

S.M. and K. Yamawaki, PTP127 (2012); arXiv:1201.4722; arXiv: 1203.xxxx.

TD in 1FM @ LHC

W,Z

W,Zq,l

q,l

g

γ

g

γ

φ

φ

φ

φ

Q,q

F, fgφ

gφ

gφ

gφ

di-weak bosons

quark, lepton pairs

digluon

diphoton >> W -loops

suppressed

suppressed

enhanced

enhanced

v.s SM Higgs

TQ contributions

EM-charged TF contributions

σ(pp TD) x BR(TD X ) at LHC

* Production: GF process >> VBF, others

* dominant decay channels: 110 GeV < Mφ < 2 Mw gg mode

2 Mw < Mφ < 2 Mp3 WW, ZZ modes

2 Mp3 < Mφ< 600 GeV P3 (color-triplet TPs)

( ～ 400 – 500 GeV)

LHC limits on TD

ZZ

ATLAS03/07/12

CMS03/07/12

* 140 GeV < M < 600 GeV excluded

* large WW, ZZ signals enhanced by GF (TQ loops)

σ(pp TD) x BR(TD WW/ZZ )/σ(SMHiggs)

WW

* large diphoton signal enhanced by large GF σ > ～ O(fb) *non-resonant signature (huge TD width)

* decays to WW,ZZ, ttbar suppressed (di-P3 dominant)

Above 600 GeV:

TD at around 125 GeV

* Only diphoton signal enhanced (depending on N_TC)

* The signal strengths (γγ, WW*,ZZ*) are in good agreement with the best-fit ones!! (within 1 σ errors)

* If only diphoton excess will develop may be discovery of 125 GeV TD

WW* ZZ* γγ

Summary* TD is a characteristic light scalar in WTC.

* The couplings to the SM particles take essentially the same

forms as those for the SM Higgs, though the coupling

strengths depend on models of WTC .

* The salient (1FM) TD LHC signatures are seen only in the diphoton channels either at ～ 125 GeV or above 600 GeV, in sharp contrast to the SM Higgs, to be tested soon this year!

Back up slides

Technicolor

Dynamical EW(chiral) SB

Dynamical W,Z mass generation

W,Z W,Z

Dynamical explanation of origin of mass

Weinberg (‘76), Susskind (‘79)

Technicolor should not be QCD-like at all

Extended TC: SM fermion mass generation

ETC

FCNC constraint

ETC

e.g.

Naive scale-up of QCD:

Needs enhancement by Holdom (1981)

associated w/ strange quark mass

S parameter

Other pheno. issues in TC scenarios

: # EW doublets Cf: S(exp) < 0.1 around T =0

One resolution: ETC-induced “delocalization” operator

too large!

ETC

vector channel

in low-energyw/

modifies SM f-couplings to W, Zcontributes to S “negatively”

Chivukula et al (2005)

Top quark mass generation

ETC

too small!

One resolution: Strong ETCMiransky et al (1989)

ETC scale associated w/ top mass

--- makes induced 4-fermi (tt UU) coupling large enough to trigger chiral symm. breaking (almost by NJL dynamics)

boost-up

T parameter(Strong) ETC generates large isospin breaking highly model-dependent issue

One-family model (1FM)

One-doublet model (1DM)Total # of techni-fermions

Farhi et al (1981)

Appelequist et al (1996)

w/ critical # for mass generation in WTC

The TD effective Lagrangian

* Nonlinear realization for both scale and chiral symmetries

TD field φ embedded in nonlinear base Χ for scale symmetry:

trans. linearly w/ scale dim. 1

trans. nonlinearly

chiral pion field π (w/ scale dim. 0) embedded in usual chiral field U (w/ scale dim. 1):

* scale symm. broken spontaneously & explicitly by mF:

“Spurion field S” introduced so as to compensate scale-invariance

s.t. Χ coupling to operator w/ scale dim. Δ goes like

* TD arises from FF as

For Δ = 4

For Δ = 4

Compasate scale-invarinace By spurion “S”

* Nonlinearly scale & chiral inv. Lagrangian w/ “S” included

* Potential term: reproduce the proper scale anomaly/PCDC

w/

LET corresponding to

TD couplings are reproduced